Computer-based redesign of a protein folding pathway

Area of Science:

• Protein folding dynamics
• Computational protein design
• Biophysics

Background:

• Protein folding pathways are crucial for function.
• Understanding and redesigning these pathways is a fundamental challenge in protein science.
• Protein G's folding pathway involves specific beta-turn formations.

Purpose of the Study:

• To rationally redesign the protein folding pathway of Protein G.
• To investigate the effects of altering the rate-limiting step in folding.
• To enhance protein stability and folding kinetics through computational design.

Main Methods:

• Utilized a computer-based design strategy to identify optimal backbone conformations and amino acid sequences.
• Focused on maximizing interaction density in the first beta-hairpin.
• Introduced 11 amino acid replacements to engineer protein variants.

Main Results:

• Two engineered variants of Protein G were created with 11 amino acid replacements.
• The redesigned proteins exhibited approximately 4 kcal mol-1 greater stability compared to wild type.
• Kinetic studies revealed a 100-fold increase in folding speed for the engineered variants.

Conclusions:

• The study successfully switched the folding pathway of Protein G.
• The rate-limiting step was altered, with the first beta-turn forming and the second being disrupted.
• Computational design offers a powerful approach to engineer protein folding pathways, stability, and kinetics.